Using wide-band-gap BiOCl to greatly enhance the photocarriers separation of AgI via in-situ Ag bridge: Interfacial electron transfer route, density functional theory calculation and mechanism study

Abstract

For wide-band-gap semiconductor heterojunctions such as BiOCl, the empty conduction band (CB) can act as an electron capture center to improve the separation efficiency of photocarriers, which has been considered a promising strategy for the construction of efficient composite photocatalysts. However, the interface resistance of heterojunctions immediately affects their photocatalytic activity. Herein, a well-designed AgI/Ag/BiOCl photocatalyst was constructed during the photocatalytic process, using Ag as the electron bridge to reduce interface resistance and the empty CB of BiOCl as the electron capture center, to continuously capture and shed electrons. The as-prepared AgI/Ag/BiOCl with a feeding molar ratio of Ag/Bi = 0.4 presented excellent visible light photocatalytic performance for the degradation of antibiotic tetracycline (TC) and colorless phenol, which could be mainly ascribed to the synergetic effects of a Ag bridge and the electron trapping center of BiOCl. In addition, the AgI/Ag/BiOCl also showed a desirable removal rate of TC in actual wastewater or in the presence of some electrolytes, and a logical photocatalytic mechanism was explored in detail by DFT calculations. This study illustrates the adhibition of the in-situ Ag bridge and offers a new strategy for the design of efficient catalysts for the photocatalytic elimination of organic contaminants.